Reversible impulse coupling



Feb. 13, 1934. DUNHAM ET AL 1,947,126

REVERSIBLE IMPULSE COUPLING Filed Oct. 15, 1932 3 Sheets-Sheet l unham ATTORfi Feb. 13, 1934. s DUNHAM ETAL 1,947,126

REVERSIBLE IMPULSE COUPLING Filed Oct. 15, 1932 3 Sheets-Sheet 2 T 1mm CIIH N i 5mm; Leroy. 6.13am Harri. flr A'urv F Faber/Jar? Feb. 13, 5 DUNHAM ET AL v REVERS IBLE IMPULSE COUPLING Filed Oct. 15, 1932 3 Sheets-Sheet 3 INVENTORS. Z y. 5. Dunham fir/hun FPober/som Patented Feb. 13, 1934 UNITED STATES PATENT ()FFICE Leroy S. Dunham, East Orange, and Arthur F.

Robertson, Belleville, N. J assignors to Edison- Splitdorf Corporation, West Orange, N. J., a corporation of New Jersey Application October 15, 1932. Serial No. 637,960

14 Claims.

In starting internal combustion engines, particularly where they are not equipped with special cranking devices, the rotative speed is usually low at the time when the engine is going over compression, which is approximately the time for firing the charge in the cylinder under compression. When a magneto ignition generator is used for ignition purposes, this low rotating speed at the compression period is detrimental to getting a good spark from the magneto.

In order to overcome this difficulty, the magneto is equipped with an impulse starter coupling whereby the rotatable member of the magneto may be held from rotating against the tension of a spring, and then released at a predetermined point just after the piston in the cylinder under compression has passed its dead center point. When the magneto rotatable member is released, it is rapidly returned to its normal operating position under the driving power of the impulse spring, with the result that a hot spark is produced at the spark-plug in the proper cylinder.

Impulse starter couplings for ignition generators as generally used, function for one direction of rotation only. If the generator is to be driven in the opposite direction, certain changes or re-arrangement of parts must be made in the assembly of the impulse coupling in order to adapt it for this diiierent direction of rotation. Hence there are in use in the trade, right and left-hand impulse couplings, depending upon the direction of rotation of the generator to which they are to be applied.

85 One of the objects of our invention is to provide a design of impulse coupling which will function in either direction of rotation without making any changes therein, assuming of course that the generator will deliver its sparks in either di- 4c rection of rotation.

Also, another object of our invention is to pro vide an impulse coupling which will be interchangeable on a variety of generators, some of which rotate in one direction and some in the opposite direction. Such a reversible impulse starter will thereby save much time and expense not only in the construction of the device itself, but in the simplification of application in use of the impulse coupling.

In certain types of internal combustion engines; namely those generally referred to as stationary engines, it is common practice to start such an engine by the operator taking hold of the flywheel and rocking the engine backwardly and releasing the flywheel against the compression built up in the cylinder, it being understood that the rock-back is in a cylinder in which the piston was advanced beyond the dead center position in its normal direction of rotation. Under this method of operation, starting is rendered difh ficult by the slow rotative speed of the magneto rotor or armature, and by the further fact that as compression is built up in the cylinder, the operation is slowed down to zero at about the time the greatest pressure that is practical to attain is reached. In order to overcome this diificulty, we have worked out a design of impulse coupling which can be utilized for this reverse or rock-back method of cranking the engine, by producing a spark at this point of low rotational ?0- speed; but, in addition, the coupling will continue to carry on the impulse action for the necessary number of revolutions of the engine to start it into normal operation in the proper direction, or until such time as the engine has reached a speed Where the impulse starter is not needed.

It is therefore a further object of our invention to provide an impulse coupling which will function, without change, either for the normal direction of rotation of the generator, or for the special case of starting by reason of the rockback action.

While attaining the stated objects of our invention, other and ancillary objects will appear to one familiar with devices 01' this kind.

In the attached drawings:

Figure 1 is a view of an impulse coupling which produces an impulse action twice per complete revolution, and. one which is entirely reversible as to rotation. This form shows what may be considered the fundamental idea of a reversible coupling from which the other forms to be referred to are really derived.

Figure 2 shows one of the derivative forms in 96 which a single pawl and double-nosed cam on the driving member of the coupling are arranged to function with a magneto giving one spark per revolution for either direction of rotation.

Figure 3 is a view similar to Figure 2, but show- 100 ing the pawl in engagement with the stop for the normal operation of the generator.

Figure 4 is a fragmentary view of the coupling looking down on the pawl used in Figure 2.

Figure 5 is a rear view of the coupling shown in Figure 2.

Figure 6 shows a still further modified form of coupling which functions the same as the cou-.. pling shown in Figure 14, but in which a single double-nose pawl is used. 1

Figure '7 is a rear view of the coupling shown in Figure 6.

Figure 8 is a top plan view of Figure 7.

Figure 9 is a side-elevation of another form of our impulse coupling shown attached to the frame of a magneto.

Figure 10 is a front view of Figure 9, showing certain parts of the impulse coupling in two posi tions of operation under the normal way of starting.

Figure 11 is a view looking at the back of the impulse coupling device.

Figure 12 is a view on the line 12-12 of Figure 11.

Figure 13 is a plan view of that section of the driving member carrying one of the pawls.

Figure 1 1 is an end-view of the impulse coupling of Figures 9 to 11 inclusive, when used according to the method of starting wherein the flywheel is rocked backwards against compres- .sion.

Figure 15 is an end view of our impulse coupling showing a method of housing the same.

Figure 16 is a part-section and part-side elevation on the line lei--16 of Figure 15.

Figure 1'7 is a fragmentary side elevation of one of the stop plates used in the form shown in Figures 15 and 16.

Figure 18 is a plan view looking toward the bottom of Figure 17.

, Figure 19 is a side elevation of the reverse rotation stop member shown in Figures 15 and 16.

Figure 20 is a part plan view looking at the bottom of Figure 19.

Figure 21 is a vertical section through the impulse coupling rotating members.

Figure 22 is a section through the driving member only, on the lines 22-22 of Figure 21.

In the drawings, wherein like numbers refer to corresponding parts in the different views, and referring first to the generic idea illustrated in Figure l, we have shown in this figure a construction in which the driving member of the coupling is provided with two pawls 52 and 53 for engaging a stop member 5 which is fastened to a stationary part of the ignition generator. The driving member is also provided with cams 54 and for engaging the pawls 52 and 53. In this general case, the impulse coupling is of the complete reversible type; that is, it will operate for either direction of rotation of the magneto, which it is understood is of a construction which will deliver its sparks to correspond with the functioning of the impulse coupling.

Starting with the generic idea of a reversible type of impulse coupling, we will now describe certain modifications that may be made therein in order to utilize the same for producing impulse sparks when the engine, considering a single cylinder two-cycle engine requiring one spark per revolution, is to be started by cranking in the normal direction of rotation.

Considering first the coupling shown in Figures 9 to 14 inclusive, the dotted line 1 indicates the end frame member of a magneto to which is attached, by means of set screws 2, a plate 3. The plate 3 has an outwardly projecting arm 4 from which a depending lug 5 extends downwardly toward the rotor shaft 6 and into the path of move- V 7 and 8 are bent so that their ends project through notches 13 and 14 in the flange 15' far enough to intercept or strike against the lug 5. 'lange 15 then acts as a guide and support for the pawls; for the width of the notches 13 and 14 is such that the side pressure on the pawls will cause them to engage the side-walls of said notches. The pawls 7 and 8 may have slots 2'? to receive a light spring 28 for a purpose which will be hereinafter referred to.

The flange 15 comprises part of the driven member 16 of the impulse coupling which is keyed to and fastened to the 6 by a special nut 1'? which is adapted to be positioned in a recess 18 in the driving 1:), the nut having a projecting part so to engage the seat 21 on the driven member to force it on to the tapered shaft of the magneto and hold the impulse cou 1g in position in the usual way.

The driving member 19 (see Figs. 21 and 22) is provided with a recess 22 within which is positioned an impulse spring 23, the ends of which. are seated against ball members 24 positioned within th recesses by the indented portions 25. To the driven member 16, is fastened a pin 26, the free nd of which is normally positioned between the balls 24 as shown by the dotted circle in Figure 22.

Assuming the first method of operation; that is, cranking of the engine in the direction in which it is to rotate, the cam 35 on the driving member 19 will be in the position shown in full line in Figure 10, and the pawl 7 will engage the lug 5. Continuing the rotation of the driving member 19 will carry the cam 35 to the position shown by the dotted line 37 in Figure 10, tensioning the spring 23 through the medium of the pin 26 carried by the driven member 16 which engages one of the balls 24, causing it to compress the spring against the other ball or abutment 24.

As soon as the cam 35 reaches the position indicated by the dotted line 37, it will raise the pawl '7 so that it will pass the lug 5, at which instant the rotating element of the magneto will quickly advance and the magneto will produce a hot spark, and if the engine starts on the first of these impulses, centrifugal force will throw the pawls 7 and 8 out of the of the lug 5. If the first impulse does not start the engine, the rotating members of will pass the lug 5 by reason of the beveled portion 39 on the pawl 8 which, in striking the lug 5, will rotate the pawl about its pivot pin 11 so that it will pass the lug 5 and bring the parts into the position previously described for an impulse the normal direction of rotation. The springs 28 act on the pawls 7 and 8 to insure that they will move to impulsing position when the rotor speed reaches a low value. They also act to prevent rattling of the pawl or pawls.

In order to utilize the impulse coupling for the second condition; that is, of starting the engine by rocking it backward, the pawl 8 is disposed at an angular distance from the pawl '1',

and in the beginning of this action, the cam 35 The I. 5

the magneto must be turned to give another impulse and the pawl 8 7 and the engine .will then turn in the normal direction of rotation under the impulse of this explosion. i

It may be noted in passing, that the flange 15 of the driven or magneto shaft member 16 is provided with a notch or slot 41 wide enough to clear the lug 5 for the purpose of assembling the coupling on the magneto.

In the form of impulse coupling shown in Figures 2 to 5 inclusive, a single pawl 42 is pivoted by the pin 11 to the lugs 12 on the back of the driven member 16, similarly to the pawls 7 and. 8 shown in Figure 11. The driving member 19, however, is provided with two cams 43 and 44 so positioned as to release the pawl 42 from engagement with the stop member 5 in the manner indicated in Figures 2 and 3. For example, in Figure 2, the pawl 42 is shown in engagement with one side of the stop member 5,, and the cam 44 is shown in the position which it will occupy just as the pawl 42 engages the stop 5. The dotted line 45 indicates the cam 44 turned to the position just as it is about to engage the pawl 42 to lift it out of engagement with the stop 5. This is a condition brought about by the reverse direction of rotation of the magneto, regardless of the purposes for reversing the direction of rotation. If the rock-back method is desired, then the cams 43 and 44 and the stop member 5 will be proportioned to meet this condition.

In Figure 3, the cam 43 is indicated in the position it occupies just as the pawl 42 engages the stop 5 when the engine is being cranked. The dotted line 46 shows the position of the cam 43 when the driving member has been turned into position to start the release of the pawl 42, whereby the impulse spring 23 will be caused to function in the manner heretofore described.

In Figures 6, 7, and 8, we have indicated a modification of the coupling in which a single cam 35 on the driving member is used as in Figure 10, and also in which a single pawl 4'7 is attached to the driven member 16, the pawl 4'7 having two noses 48 and 49 for engaging the stop member 5, according to whether the engine is cranked in its normal running direction or by the rockback method. It will be noted from Figure 6 that the flange 15 is cut away at an angle 50 so as to act as abutment for the angular surfaces 51 on the pawl noses 48 and 49 in the manner described for pawls 7 and 8 in Figures 10, 11, and 14.

Figures 15 and 16 show the, same impulse coupling and parts in the same position as in Figure 14, but the coupling is enclosed within a housing 29 fastened to the magneto 1 by similar cap screws 2. The exterior part of the housing 29 is closed by the amiular plate 30 fastened to the housing 29 by screws 31 and a ring 32 having a flange 33 fitting within an orifice in the plate 30. The ring 32 is fastened to the plate 30 by means of screws 34 passing through slots 36, which arrangement allows the ring 32 to have a small rotary adjustment around the coupling members. This adjustment is preferably fixed by reason of the serrations 38 arranged in a portion of the periphery of the ring 32. A cooperating pawl member 56 having serrations 38 is positioned in a slot in the casing 29 and ring 32, being held in position by the screw 57 and lock-washer 58. The ring 32 is provided with a stop portion 59 of the flange 33 which is in the path of movement of the pawl 8 when the rock-back" method of cranking is used.

When the engine is cranked or turned in its normal direction of rotation, the pawl 7 will engage the stop flange 60 on the plate 30, causing the impulse coupling to function as has been previously described. It may be noted in passing that the ring 32 is provided with an inner annular recess within which is placed a packing ring 61 which is adapted tocontact with the outer periphery of the driving member 19 to keep dust and dirt from entering the housing 29.

From what has been said, it will be seen that we have provided at least three ways in which an impulse coupling can be constructed to take care of the condition in which the engine may be cranked with the impulse coupling turning in the normal direction of rotation, and at the same time used to crank the engine by the rock-back method. These three ways may be summed up as follows:

(1) Double-pawl and single-cam arrangement.

(2) Double-cam and single-pawl arrangement.

(3) Single-pawl and single-cam arrangement.

It will be evident from what has been said that many of the details of construction may be varied'without departing from our invention or the scope of the appended claims.

Having thus described our invention, what we claim is:

1. A reversible impulse coupling for an ignition generator including driving and driven members, a pair of L-shaped pawls arcuately spaced and pivotally mounted on the driven member, one arm of the L extending over the outer periphery of the driving member to engage a stop carried by the generator, one pawl engaging the stop when the couplng is slowing turned in one direction, and the other pawl to engage the stop when the coupling is slowly turned in the opposite direction, a spring housed within said members and put under tension by the driving member when the driven member is stopped by one of the pawls engaging said step, and a cam for releasing the pawl engaged by the stop, whereby said spring under tension will deliver a sudden impulse to the driven member.

2. An impulse coupling as set forth in claim 1, characterized in that the driven member has a flange with notches therein withinwhich the extending parts of the pawls lie.

3. An impulse coupling as set forthin claim 1,

characterized in that the driven member has a flange with notches therein within which the extending parts of the pawls lie, further characterized in that springs are associated with each pawl for the purposes described.

4. An impulse coupling as set forth in claim 1, characterized in that the driven member has a flange with notches therein within which the extending parts of the pawls lie, further characterized in that springs are associated with each pawl for the purposes described, and still further characterized in that said pawls are beveled in opposite directions for the purpose described.

5. An impulse coupling as set forth in claim 1, characterized in that the driven member has a flange with notches therein within which the extending parts of the pawls lie, and further characterized in that said flange has an extra notch therein to pass said stop, whereby the coupling may be assembled on the generator shaft.

6. A reversible impulse coupling for an ignition generator including driving and driven members, an L-shaped pawl having stop-engaging portions arcuately spaced according to the sparking position of the rotatable member of the generator, said pawl being mounted so as to engage stopping means to stop the driven member from rotation, one stop portion of the pawl acting for one direction of rotation and the other p0rtion for the opposite direction of rotation, an impulse spring tensioned by the driving member when the driven member is restrained by one of said pawls, and means on the driving member for releasing the restraining pawl.

7. An impulse coupling as set forth in claim 6, characterized in that the pawl is constructed so successive impulses may be given by the coupling until the engine starts, when the pawl is automatically moved from stopping position.

8. An impulse coupling for an ignition generator including driving and driven members, a pawl having stop-engaging portions arcuately spaced according to the sparking position of the rotatable member of the generator, said pawl being mounted so as to engage stopping means to stop the driven member from rotation, one of said stopengaging portions acting for one direction of rotation and the other engaging portion acting for the opposite direction of rotation, an impulse spring tensioned by the driving member when the driven member is restrained by one of said stopengaging portions, and means carried by the driving member for releasing the pawl from restraining position.

9. An impulse starting coupling for an ignition generator including driving and driven members, pawls arcuately spaced and mounted on the driven member to move in a plane radial to the axis of the generator so as to engage a stop carried by the generator, a spring put under tension by the driving member when the driven member is held by a pawl engaging said stop, and means carried by the driving member for releasing said pawl from engagement with the stop, whereby said spring will apply a sudden impulse to the driven member the coupling being further characterized in that the pawls, release means and stop are co-related so the generator may be turned in either direction of rotation without changing the location of the several parts of the mechanism for the purpose described.

10. An impulse starting coupling including driving and driven members having resilient means operatively interposed therebetween and adapted to be stressed by relative movement between said members on rotation of the driving member in either direction, means mounted on the driven member to intermittently move in a plane radial to the axis of rotation thereof, to engage a stop and restrain the driven member over a predetermined angular movement of the driving member, and means on the driving member to release the engaging means from said stop.

11. An impulse coupling as set forth in claim 10, characterized in that a multiple piece housing is provided for the coupling parts, one of said housing pieces carrying a stop for the driven member for one direction of rotation, and another housing piece carrying a stop for the driven member for the opposite direction of rotation.

. 12. An impulse coupling as set forth in claim 10, characterized in that a multiple piece housing is provided for the coupling parts, one of said housing pieces carrying a stop for the driven member for one direction of rotation, and another housing piece carrying a stop for the driven member for the opposite direction of rotation, and further characterized in that one of said housing pieces is adjustable to arcuately vary the position of its stop.

13. An impulse coupling including driving and driven members, means carried by the driven member to move in a plane radial to the axis of rotation thereof and effective, irrespective of the direction of rotation, to engage a stop and restrain said driven member during a predetermined amount of rotation of the driving member in either direction of rotation, resilient means acting between the driving and driven members to rapidly move the driven member from restrained position, and cam means on the driving member to release the driven member from restrained position.

14. An impulse coupling as set forth in claim 13, further characterized in that two different stop surfaces are provided, one for one direction of rotation and the other for the opposite rotation of the said drivingand driven members.

LEROY S. DUNHAM. ARTHUR F. ROBERTSON.

IOU 

